Does that mean that there's also a "maximal GWES" variable? If I set the minimal GWES variable, what is going to be different compared to when I don't do it? Does anyone know?
I don't have all the options in mind, it's been a long time, but here is what I remember:
Windows uses window messages for other purposes than GUI apps, it's also the foundation for calls queues of single-threaded apartment COM objects, and other pieces of code can use a message pump as a simple queueing system.
Windows CE could support headless devices, where the GUI and GDI infrastructure would just be a waste of ROM. But it needed to still support message-only windows for COM STA and other code using those.
So there was a minimal GWES that only supported message queues, but without any dependency or support for GUI features.